In single-star evolution a LTP (a post-AGB helium shell flash while hydrogen still burns) takes place hundreds to thousands of years after departure from the AGB (e.g., [1]}). For a VLTP (when hydrogen burning has already ceased) the star needs to fade first to a luminosity of \(L_{\rm VLTP} \approx {\rm few} \times 100 L_\odot \)  along the WD cooling track (e.g., [2]}, [1]}). This implies that VLTPs take place tens of thousands of years after departure from the AGB, with longer timescales for more massive stars (e.g., [4]}, [5]}, for evolutionary times on the WD cooling track). Overall, I crudely take the LTP/VLTP of the merger remnant to occur sometime in the post-AGB age of
\(100 {~\rm yr}t_{\rm AGB-TP} 10^5 {~\rm yr}.\) 
